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author | Lennart Poettering <lennart@poettering.net> | 2018-06-25 19:16:43 +0200 |
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committer | Lennart Poettering <lennart@poettering.net> | 2018-09-25 15:57:47 +0200 |
commit | 2ac2ff3fc1af850bf5159a652cf0005f634aebf9 (patch) | |
tree | 1b14a9d596b16faf73c2977799a0ee4dd334e00e /src/basic/utf8.c | |
parent | 7c4218578466e128a9cff42ff95d58deab16637e (diff) | |
download | systemd-2ac2ff3fc1af850bf5159a652cf0005f634aebf9.tar.gz |
utf8: let's update utf16_to_utf8() a bit
Let's change utf16_to_utf8() prototype to refer to utf16 chars with char16_t rather than void
Let's not cast away a "const" needlessly.
Let's add a few comments.
Let's fix the calculations of the buffer size to allocate, and how long
to run the loop in case of uneven byte numbers
Diffstat (limited to 'src/basic/utf8.c')
-rw-r--r-- | src/basic/utf8.c | 23 |
1 files changed, 15 insertions, 8 deletions
diff --git a/src/basic/utf8.c b/src/basic/utf8.c index f6ab26d826..7dc84c1157 100644 --- a/src/basic/utf8.c +++ b/src/basic/utf8.c @@ -314,18 +314,25 @@ size_t utf8_encode_unichar(char *out_utf8, char32_t g) { return 0; } -char *utf16_to_utf8(const void *s, size_t length) { +char *utf16_to_utf8(const char16_t *s, size_t length /* bytes! */) { const uint8_t *f; char *r, *t; - r = new(char, (length * 4 + 1) / 2 + 1); + assert(s); + + /* Input length is in bytes, i.e. the shortest possible character takes 2 bytes. Each unicode character may + * take up to 4 bytes in UTF-8. Let's also account for a trailing NUL byte. */ + if (length * 2 < length) + return NULL; /* overflow */ + + r = new(char, length * 2 + 1); if (!r) return NULL; - f = s; + f = (const uint8_t*) s; t = r; - while (f < (const uint8_t*) s + length) { + while (f + 1 < (const uint8_t*) s + length) { char16_t w1, w2; /* see RFC 2781 section 2.2 */ @@ -335,13 +342,13 @@ char *utf16_to_utf8(const void *s, size_t length) { if (!utf16_is_surrogate(w1)) { t += utf8_encode_unichar(t, w1); - continue; } if (utf16_is_trailing_surrogate(w1)) - continue; - else if (f >= (const uint8_t*) s + length) + continue; /* spurious trailing surrogate, ignore */ + + if (f + 1 >= (const uint8_t*) s + length) break; w2 = f[1] << 8 | f[0]; @@ -349,7 +356,7 @@ char *utf16_to_utf8(const void *s, size_t length) { if (!utf16_is_trailing_surrogate(w2)) { f -= 2; - continue; + continue; /* surrogate missing its trailing surrogate, ignore */ } t += utf8_encode_unichar(t, utf16_surrogate_pair_to_unichar(w1, w2)); |